Introducing an UnknownLanguage

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/TypeManager.kt

@@ -183,7 +183,7 @@ class TypeManager {
     fun createOrGetTypeParameter(
         templateDeclaration: TemplateDeclaration,
         typeName: String,
-        language: Language<*>?
+        language: Language<*>
     ): ParameterizedType {
         var parameterizedType = getTypeParameter(templateDeclaration, typeName)
         if (parameterizedType == null) {

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/frontends/UnknownLanguage.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2024, Fraunhofer AISEC. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *                    $$$$$$\  $$$$$$$\   $$$$$$\
+ *                   $$  __$$\ $$  __$$\ $$  __$$\
+ *                   $$ /  \__|$$ |  $$ |$$ /  \__|
+ *                   $$ |      $$$$$$$  |$$ |$$$$\
+ *                   $$ |      $$  ____/ $$ |\_$$ |
+ *                   $$ |  $$\ $$ |      $$ |  $$ |
+ *                   \$$$$$   |$$ |      \$$$$$   |
+ *                    \______/ \__|       \______/
+ *
+ */
+package de.fraunhofer.aisec.cpg.frontends
+
+import de.fraunhofer.aisec.cpg.graph.types.Type
+import kotlin.reflect.KClass
+
+/**
+ * Represents a language definition with no known implementation or specifics. The class is used as
+ * a placeholder or to handle cases where the language is not explicitly defined or supported.
+ */
+object UnknownLanguage : Language<Nothing>() {
+    override val fileExtensions: List<String>
+        get() = listOf()
+
+    override val namespaceDelimiter: String
+        get() = ""
+
+    override val frontend: KClass<out Nothing> = Nothing::class
+    override val builtInTypes: Map<String, Type> = mapOf()
+    override val compoundAssignmentOperators: Set<String> = setOf()
+}
+
+/**
+ * Represents a composite language definition composed of multiple languages.
+ *
+ * @property languages A list of languages that are part of this composite language definition.
+ */
+class MultipleLanguages(val languages: Set<Language<*>>) : Language<Nothing>() {
+    override val fileExtensions = languages.flatMap { it.fileExtensions }
+    override val namespaceDelimiter: String = ""
+    override val frontend: KClass<out Nothing> = Nothing::class
+    override val builtInTypes: Map<String, Type> = mapOf()
+    override val compoundAssignmentOperators: Set<String> = setOf()
+}

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/Component.kt

@@ -26,6 +26,8 @@
 package de.fraunhofer.aisec.cpg.graph
 
 import de.fraunhofer.aisec.cpg.PopulatedByPass
+import de.fraunhofer.aisec.cpg.frontends.MultipleLanguages
+import de.fraunhofer.aisec.cpg.frontends.UnknownLanguage
 import de.fraunhofer.aisec.cpg.graph.declarations.TranslationUnitDeclaration
 import de.fraunhofer.aisec.cpg.graph.edges.ast.astEdgesOf
 import de.fraunhofer.aisec.cpg.graph.edges.unwrapping
@@ -54,6 +56,14 @@ open class Component : Node() {
     @Synchronized
     fun addTranslationUnit(tu: TranslationUnitDeclaration) {
         translationUnits.add(tu)
+
+        // Check, if this component is of a particular single language or multi-language
+        val languages = translationUnitEdges.map { it.end.language }.toSet()
+        if (languages.size == 1) {
+            this.language = languages.singleOrNull() ?: UnknownLanguage
+        } else if (languages.size > 1) {
+            this.language = MultipleLanguages(languages = languages)
+        }
     }
 
     /**

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/Interfaces.kt

@@ -37,7 +37,7 @@ import de.fraunhofer.aisec.cpg.sarif.PhysicalLocation
 /** A simple interface that a node has [language]. */
 interface HasLanguage {
 
-    var language: Language<*>?
+    var language: Language<*>
 }
 
 /** A simple interface that a node has [name] and [location]. */

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/Node.kt

@@ -32,6 +32,7 @@ import de.fraunhofer.aisec.cpg.TranslationContext
 import de.fraunhofer.aisec.cpg.TypeManager
 import de.fraunhofer.aisec.cpg.frontends.Handler
 import de.fraunhofer.aisec.cpg.frontends.Language
+import de.fraunhofer.aisec.cpg.frontends.UnknownLanguage
 import de.fraunhofer.aisec.cpg.graph.declarations.MethodDeclaration
 import de.fraunhofer.aisec.cpg.graph.declarations.RecordDeclaration
 import de.fraunhofer.aisec.cpg.graph.declarations.TranslationUnitDeclaration
@@ -93,7 +94,7 @@ abstract class Node :
      */
     @Relationship(value = "LANGUAGE", direction = Relationship.Direction.OUTGOING)
     @JsonBackReference
-    override var language: Language<*>? = null
+    override var language: Language<*> = UnknownLanguage
 
     /**
      * The scope this node "lives" in / in which it is defined. This property is set in

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/NodeBuilder.kt

@@ -59,7 +59,7 @@ interface MetadataProvider
  * each [Node], but also transformation steps, such as [Handler].
  */
 interface LanguageProvider : MetadataProvider {
-    val language: Language<*>?
+    val language: Language<*>
 }
 
 /**

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/declarations/ValueDeclaration.kt

@@ -27,6 +27,7 @@ package de.fraunhofer.aisec.cpg.graph.declarations
 
 import de.fraunhofer.aisec.cpg.PopulatedByPass
 import de.fraunhofer.aisec.cpg.frontends.Language
+import de.fraunhofer.aisec.cpg.frontends.UnknownLanguage
 import de.fraunhofer.aisec.cpg.graph.*
 import de.fraunhofer.aisec.cpg.graph.edges.flows.Usages
 import de.fraunhofer.aisec.cpg.graph.edges.unwrapping
@@ -44,11 +45,11 @@ abstract class ValueDeclaration : Declaration(), HasType, HasAliases {
 
     override val typeObservers: MutableSet<HasType.TypeObserver> = identitySetOf()
 
-    override var language: Language<*>? = null
+    override var language: Language<*> = UnknownLanguage
         set(value) {
             // We need to adjust an eventual unknown type, once we know the language
             field = value
-            if (value != null && type is UnknownType) {
+            if (type is UnknownType) {
                 type = UnknownType.getUnknownType(value)
             }
         }

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/statements/expressions/Expression.kt

@@ -26,6 +26,7 @@
 package de.fraunhofer.aisec.cpg.graph.statements.expressions
 
 import de.fraunhofer.aisec.cpg.frontends.Language
+import de.fraunhofer.aisec.cpg.frontends.UnknownLanguage
 import de.fraunhofer.aisec.cpg.graph.*
 import de.fraunhofer.aisec.cpg.graph.statements.Statement
 import de.fraunhofer.aisec.cpg.graph.types.*
@@ -49,11 +50,11 @@ import org.neo4j.ogm.annotation.Transient
 abstract class Expression : Statement(), HasType {
     @Transient override val typeObservers: MutableSet<HasType.TypeObserver> = identitySetOf()
 
-    override var language: Language<*>? = null
+    override var language: Language<*> = UnknownLanguage
         set(value) {
             // We need to adjust an eventual unknown type, once we know the language
             field = value
-            if (value != null && type is UnknownType) {
+            if (type is UnknownType) {
                 type = UnknownType.getUnknownType(value)
             }
         }

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/AutoType.kt

@@ -35,7 +35,7 @@ import de.fraunhofer.aisec.cpg.graph.unknownType
  *
  * Note: This is intentionally a distinct type and not the [UnknownType].
  */
-class AutoType(override var language: Language<*>?) : Type("auto", language) {
+class AutoType(override var language: Language<*>) : Type("auto", language) {
     override fun reference(pointer: PointerType.PointerOrigin?): Type {
         return PointerType(this, pointer)
     }

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/BooleanType.kt

@@ -31,6 +31,6 @@ import de.fraunhofer.aisec.cpg.frontends.Language
 class BooleanType(
     typeName: CharSequence = "bool",
     bitWidth: Int? = 1,
-    language: Language<*>? = null,
+    language: Language<*>,
     modifier: Modifier = Modifier.NOT_APPLICABLE
 ) : NumericType(typeName, bitWidth, language, modifier)

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/FloatingPointType.kt

@@ -31,6 +31,6 @@ import de.fraunhofer.aisec.cpg.frontends.Language
 class FloatingPointType(
     typeName: CharSequence = "",
     bitWidth: Int? = null,
-    language: Language<*>? = null,
+    language: Language<*>,
     modifier: Modifier = Modifier.SIGNED
 ) : NumericType(typeName, bitWidth, language, modifier)

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/FunctionPointerType.kt

@@ -26,6 +26,7 @@
 package de.fraunhofer.aisec.cpg.graph.types
 
 import de.fraunhofer.aisec.cpg.frontends.Language
+import de.fraunhofer.aisec.cpg.frontends.UnknownLanguage
 import de.fraunhofer.aisec.cpg.graph.types.PointerType.PointerOrigin
 import java.util.*
 import org.apache.commons.lang3.builder.ToStringBuilder
@@ -48,7 +49,7 @@ class FunctionPointerType : Type {
 
     constructor(
         parameters: List<Type> = listOf(),
-        language: Language<*>? = null,
+        language: Language<*>,
         returnType: Type = UnknownType.getUnknownType(language)
     ) : super(EMPTY_NAME, language) {
         this.parameters = parameters
@@ -58,7 +59,7 @@ class FunctionPointerType : Type {
     constructor(
         type: Type,
         parameters: List<Type> = listOf(),
-        language: Language<*>? = null,
+        language: Language<*> = UnknownLanguage,
         returnType: Type = UnknownType.getUnknownType(language)
     ) : super(type) {
         this.parameters = parameters

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/IntegerType.kt

@@ -31,6 +31,6 @@ import de.fraunhofer.aisec.cpg.frontends.Language
 class IntegerType(
     typeName: CharSequence = "",
     bitWidth: Int? = null,
-    language: Language<*>? = null,
+    language: Language<*>,
     modifier: Modifier = Modifier.SIGNED
 ) : NumericType(typeName, bitWidth, language, modifier)

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/NumericType.kt

@@ -32,7 +32,7 @@ import java.util.*
 open class NumericType(
     typeName: CharSequence = "",
     val bitWidth: Int? = null,
-    language: Language<*>? = null,
+    language: Language<*>,
     val modifier: Modifier = Modifier.SIGNED
 ) : ObjectType(typeName, listOf(), true, language) {
 

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/ObjectType.kt

@@ -60,7 +60,7 @@ open class ObjectType : Type {
         typeName: CharSequence,
         generics: List<Type>,
         primitive: Boolean,
-        language: Language<*>?
+        language: Language<*>
     ) : super(typeName, language) {
         this.generics = generics
         isPrimitive = primitive
@@ -71,7 +71,7 @@ open class ObjectType : Type {
         type: Type?,
         generics: List<Type>,
         primitive: Boolean,
-        language: Language<*>?
+        language: Language<*>
     ) : super(type) {
         this.language = language
         this.generics = generics

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/ParameterizedType.kt

@@ -37,7 +37,7 @@ class ParameterizedType : Type {
         language = type.language
     }
 
-    constructor(typeName: String?, language: Language<*>?) : super(typeName) {
+    constructor(typeName: String?, language: Language<*>) : super(typeName) {
         this.language = language
     }
 

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/StringType.kt

@@ -29,7 +29,7 @@ import de.fraunhofer.aisec.cpg.frontends.Language
 
 class StringType(
     typeName: CharSequence = "",
-    language: Language<*>? = null,
+    language: Language<*>,
     generics: List<Type> = listOf()
 ) : ObjectType(typeName, generics, false, language) {
 

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/types/Type.kt

@@ -95,7 +95,7 @@ abstract class Type : Node {
         typeOrigin = type?.typeOrigin
     }
 
-    constructor(typeName: CharSequence, language: Language<*>?) {
+    constructor(typeName: CharSequence, language: Language<*>) {
         name =
             if (this is FunctionType) {
                 Name(typeName.toString(), null, language)
@@ -106,7 +106,7 @@ abstract class Type : Node {
         typeOrigin = Origin.UNRESOLVED
     }
 
-    constructor(fullTypeName: Name, language: Language<*>?) {
+    constructor(fullTypeName: Name, language: Language<*>) {
         name = fullTypeName.clone()
         typeOrigin = Origin.UNRESOLVED
         this.language = language